材果兼用核桃优良品系(种)综合评价及分析OA

[Objective]To expedite the selection of the breeding of new walnut varieties suitable for both timber and fruit uses in China,this study initially screened over 5000 seedlings,followed by fur-ther selection to identify 15 excellent walnut strains(varieties).Through long-term monitoring and com-prehensive evaluation of tree growth parameters and nut quality traits,excellent walnut strains(variet-ies)were identified,providing foundational germplasm and scientific support for timber-nut-dual-pur-pose walnut breeding.[Methods]This study established a 10-mu(approx.0.67 hectares)experimental orchard on the Yellow River alluvial plain in Liaocheng municipality,Shandong Province.A random-ized block design was employed.15 walnut strains grafted on Jizhaomian rootstock were used as the test materials,and cultivars Qinglin(QL),Xiangling(XL)and Qingxiang(QX),served as the controls.Among the excellent walnut strains,HL-1,HL-2 and HL-3 were derived from common walnut(Juglans regia L.)seedlings,while HL-4 to HL-15 were selected from QL seedlings.Orchard management fol-lowed the established models and complied with relevant national standards.Measured parameters in-cluded tree structural characteristics(tree height,diameter at breast height,and basal diameter)and nut traits(external morphological features and internal quality indicators such as protein,fatty acid and ami-no acid contents).Single-trait comparisons and principal component analysis(PCA)were employed for comprehensive evaluation of the timber-nut-dual-purpose characteristics.[Results]The results showed that significant differences were observed among the walnut strains in tree height(10.41-13.06 m),ground diameter(19.14-25.60 cm),and diameter at breast height(15.56-20.40 cm).Among these,HL-1 and HL-10 exhibited significantly higher values across all these traits compared to the other walnut strains and the control.Regarding crown architecture,the east-west crown span(5.46-7.10 m)was con-sistently and significantly larger than north-south span(4.59-5.85 m),with 9 walnut strains surpassing the controls in crown dimensions.Similarly,crown expansion rates demonstrated a directional trend:east-west growth(0.61-0.88 m/year)exceeded north-south growth(0.32-0.67 m/year).All the tested walnut strains displayed typical smooth shell surfaces with non-exposed kernels and generally promi-nent,tight suture lines.78.6%of the walnut strains produced elliptical nuts with pointed apexes,and 85.7%had flat bases.Kernel extraction was difficult for 64.3%of the strains,but relatively easier in HL-4,which had an exceptionally thin shell with a thickness of only 0.92 mm.In accordance with the requirements for selection of elite walnut cultivars specified in the Chinese Forestry Industry Standard(LY/T 3004.2-2018),the single nut weight of all the walnut strains(14.63-24.20 g)met the standard for elite cultivars.Notably,HL-15(24.20 g)exhibited a 16.3%higher fruit weight compared to QL.Based on the National Standard(GB/T 20398-2021),the kernel recovery of 10 walnut strains exceed-ed 40%,satisfying the quality requirements for premium walnut nuts.The highest kernel yield rate was 62.53%found in HL-4.Kernel weights across the walnut strains ranged from 6.43 g to 9.95 g.Kernel weight of HL-4(9.95 g)was 24.38%larger compared to QX(8.00 g).The protein content of all the wal-nut strains met the standards for elite cultivars.Specifically,HL-11 exhibited a protein content 3.47%higher than XL(194.66 mg·g-1);HL-12 was 0.73%higher than QL(183.74 mg·g-1);and HL-15 1.73%higher compared to QX(179.97 mg·g-1).Five walnut strains,including HL-3,HL-10 and HL-9,had a crude fat content exceeding 600 mg·g-1,meeting the elite cultivar standards.The highest level,637.11 mg·g-1,was found in HL-3,being 0.48%higher than that of QX(634.07 mg·g-1).The six wal-nut strains with high kernel recovery contained 17 amino acids.Total amino acid content ranged from 100.58 mg·g-1(HL-1)to 140.22 mg·g-1(HL-3),while essential amino acid content ranged from 27.11 mg·g-1(HL-1)to 39.00 mg·g-1(HL-3).Among these strains,HL-3,HL-8 and HL-10 exhibited a higher total amino acid content and a higher essential amino acid content compared to XL.Linoleic acid(39.89%-66.81%)was the predominant fat component,with the highest content(64.00%)found in HL-11.The oleic acid content in HL-4(42.19%)was 2.7 times that of the QX control;HL-3 was rich in α-linolenic acid(9.71%).Comprehensive evaluation using Principal Component Analysis(PCA)on tree growth in-dicators identified two principal components accounting for a cumulative variance contribution rate of 86.00%,with HL-1,HL-10 and HL-9 achieving the highest comprehensive scores.For nut quality indi-cators,four principal components yielded a cumulative variance contribution rate of 93.86%,and HL-8,HL-3 and HL-10 attained the highest comprehensive scores.Considering its outstanding performance in both tree growth and nut quality,HL-10 was determined to be an optimal candidate walnut strain for timber-nut dual purposes.[Conclusion]Based on the analysis results,it is concluded that HL-10 can be considered as a candidate line for timber-nut-dual-purpose walnut.This study successfully selected ex-cellent walnut strains combining rapid growth with high-quality nut production,providing valuable germplasm resources for industry upgrading.